Threads were left untied for Chin and Kono in the season seven finale -- the former weighing an enticing job in San Francisco, the latter on a plane to Las Vegas to right some wrongs and fulfill her legacy as a chaser of sex traffickers. Where both characters ended up are addressed by the end of the premiere.

“Chin Ho and Kono [were] really elevated because [Daniel and Grace] were so good as actors. They did a great job,” showrunner Peter Lenkov tells ET of Kim and Park. “The audience is going to miss them and their presence is going to be missed. The show is different. The dynamic is different. It’s almost necessary [that] to keep something going is to change things up.”

“At some point, you sort of feel like those stories have been told, and Daniel and Grace’s stories we mined so much because they were given so much work over seven seasons to do. We’ve told so many personal stories and gone to hell and back,” he continues. “I’m not sure in season eight what we would’ve done. In a way, it was organic to have a change of the guard.”

In an in-depth conversation, Lenkov talks at length with ET about the “rebooted” season, the new blood and why longtime fans have nothing to worry about.

ET: There were a lot of changes in front of the camera heading into season eight. What was your directive going into this new year due to the cast shuffle?

Peter Lenkov: It’s weird that it made news. If you look at shows that have been on the air for years, there are cast changes all the time, especially as you get into into later seasons. We’ve been pretty lucky to be pretty consistent with our main cast for so many years, so really, what I wanted to do was do what we’ve normally done over the years, which is keep adding and building the family. It just so happens that this year, we had two cast members leave. The characters that did leave, we acknowledge that they left. We talk about them. Emotionally, we’ve lost a little bit of ourselves because they’re gone. [Chin Ho and Kono are] very big in terms of the canon and the mythology of the show, but nothing’s drastically changed. Whether or not Daniel or Grace came back, we always had a plan of adding to the cast.

You mentioned that Chin and Kono will be acknowledged. What did you want to honor about those characters in the premiere?

We explain where they are. I’m not sure it would make any sense to not acknowledge them not being on the show, so we do very early on at least talk about where Daniel’s character is and then later, we talk about where Grace’s character is. We talk about them for a little while in the first batch of episodes. Their presence still exists and we still acknowledge that they were a big part of our family. We find ourselves talking about them every now and then, and it feels very organic. We’re not moving on as if they never existed.

In regards to how often, is it a matter of what makes sense organically?

It becomes a bigger deal when Adam comes back into the show, because we have to acknowledge the fact that him and Kono are not in the same place and why is that? So we start bringing her up again. I’m hoping one day that, after Grace spends some very good quality time with her family, maybe we could get her back on the show someday.

What are the realistic chances you see of having Daniel and Grace back one last time?

I never say never. I think there’s always that possibility. As long as they’re alive in our world, I think anything can happen.

In the premiere, Chin is revealed to have accepted the job in San Francisco leading his own task force and Kono is said to be on the mainland shutting down a sex trafficking ring. Were these endpoints where you envisioned these characters ending up at the end of the series?

Especially with Daniel’s character, Chin, I had always hoped that he would get his own task force one day. He was on a trajectory when he was in the police department as somebody who would be a leader. I think everything that happened in his life, losing his badge and getting it back, I always thought it would be nice for him to have his own task force and taking everything he’s learned under McGarrett and Five-0 to take that in a different state. That was always an endgame that was going to happen at some point, it just happened earlier when Daniel decided to leave. With Grace, [her] story is still yet to be finished so it’s still open for me.

You also have two new additions to the Five-0 task force, with Meaghan Rath as former police academy recruit Tani Rey, and Beulah Koale as ex-navy SEAL Junior Reigns. What is the new team dynamic going to be like?

They’re representing the next generation of the Five-0 task force. It was something we had always talked about: Add some younger members who, ultimately, as our characters get older and wiser and get to the age where they can mentor somebody, it’d be nice to have some young blood come in. They’re new to this. They’re well-trained. One of them was in the police academy, the other was a navy SEAL. They’re qualified and bring different skill sets to the table, and they’re enthusiastic and they fit in naturally in our universe. The way we meet them, both of them are in need of something like this -- some kind of structure in their life. They’re a little bit like broken toys, very much like the original members of Five-0 when McGarrett was collecting them. In our story, McGarrett finds them at important crossroads where this is needed and welcome in their lives.

Earlier, you mentioned Ian Anthony Dale’s return as Kono’s husband, Adam. What can you divulge about how he returns to Five-0?

The idea is that he’s supposed to be returning to the island with Kono and for reasons you discover in the [seventh] episode, he doesn’t. They’re not split up. They’re just living in different parts of the world and Adam has to realize that his wife is on this journey and this journey is her legacy and she’s got to see it through before she returns to the island. Adam is very supportive of that but he’s got to move on. He can’t just be following her around. He’s got to start his own thing.

Danno has a line at the end of the episode, where he says to Tani, “Things are changing. I’d like you to join us.” Is that the vibe you want viewers keep in the back of their minds this season?

Yeah. I want them to be open to change. When he says [that], it’s the same thing you’re saying to the audience. The show’s changing a little bit, please join us. Keep watching. I think we’re telling our best stories and I’m hoping that people accept the fact that shows can survive post-two very important characters [leaving], but hopefully they will watch the show and realize that it’s the same show, it’s just growing and aging.